Now a new problem with my Co-Star

I was watching tv last night and all of a sudden i have a whole line of pixels go out. i changed hdmi cable same problem. i plugged the the hdmi cable straight from the directtv box and the line went away so i know its the co-star box. i contacted vizio through live chat last night and they told me it was because my screen size settings were wrong. so i adjusted my screen size to match my tv but it was still there. so they told me i needed to contact my tv manufacture. i kept telling them it wasnt my tv that it was the co-star but all they would say was that they couldnt help me arrrr